f16ccb6445
Currently on execlists, we use a local hwsp for the kernel_context, rather than the engine's HWSP, as this is the default for execlists. However, seqno wrap requires allocating a new HWSP cacheline, and may require pinning a new HWSP page in the GGTT. This operation requiring pinning in the GGTT is not allowed within the kernel_context timeline, as doing so may require re-entering the kernel_context in order to evict from the GGTT. As we want to avoid requiring a new HWSP for the kernel_context, we can use the permanently pinned engine's HWSP instead. However to do so we must prevent the use of semaphores reading the kernel_context's HWSP, as the use of semaphores do not support rollover onto the same cacheline. Fortunately, the kernel_context is mostly isolated, so unlikely to give benefit to semaphores. Reported-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200210205722.794180-5-chris@chris-wilson.co.uk
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.